All week long, we've been counting down to "hunger games" blockbuster premiere. Earlier this week, josh hutcherson sat down with robin. But then, he went backstage and helped one young fan's dream... See More
All week long, we've been counting down to "hunger games" blockbuster premiere. Earlier this week, josh hutcherson sat down with robin. But then, he went backstage and helped one young fan's dream come true. All in partnership with macy's and make-a-wish's believe campaign. Chris connelly has this remarkable story. Reporter: Active and updeet, caitlin stewart of albuquerque, new mexico, could do it all. She's always been outgoing. Never, never the shy one. Just a normal, skinny kid. Very happy. Always smiling. Reporter: But then, at age 12 -- out of nowhere, I started getting pains in my right knee. Reporter: Tests led to a shocking diagnosis. Doctors said caitlin had osteo sarcoma. An aggressive form of cancer. Chemotherapy ravaged caitlin's system. She battled nausea and lost her hair. Surgery to replace her knee left her unable to walk for months. I would break down sometimes because it was hard. Reporter: Throughout her treatment, she took with her this life-sized cutout of her favorite actor, josh hutcherson, from "the hunger games" movie. He kept me happy. Reporter: With her cancer in remission, caitlin told make-a-wish, she dreams of meeting josh. That's where we stepped in. Caitlin thinks she and her family won a sweepstakes. She's given a backstage tour. But she has no idea, who is waiting to meet her. Just behind that door. Is there a caitlin in here? I'm josh. Hi. Nice to meet you. Reporter: Josh has a treat for his new friend. You guys are going to see "the hunger games: Catching fire" before it comes out. Reporter: He gives her a poster signed by the whole cast. And a gift, with special meaning for caitlin. I heard you had one. So, I got you an updated one. Reporter: It's perfect. A good-bye hug from josh, gets her a little emotional. All part of a magical wish for caitlin. From the beginning of the diagnosis of her cancer, to her getting to meet josh, it's kind of like the end of a chapter. Wow. People doing good things. There he is. Updated cutout, signed "all the best." Caitlin, it will be on the way. It will be marked super-duper fragile, not to worry. Meanwhile, everything that the make-a-wish foundation campaign has been doing, you can be a part of it. For every stamped letter to santa put in a believed box at macy's, macy's will donate a dollar to make-a-wish. Let's take a look. Look at this number. 171,250 letters. There's still time, by the way. Send your letter to santa and help a sick kid receive a gift this holiday season. How good is that? Goodmorningamerica.Com on yahoo! Logon, find all of your answers.
This transcript has been automatically generated and may not be 100% accurate.